1. A General Overview of the APRS System
Updated Jan 2006

2. General Topics APRS Definition & History Typical Equipment Setup
Mapping/Tracking Programs
Weather Reporting
Public Events
The Future
Question & Demonstration

3. What is APRS?
APRS stands for Automatic Packet Reporting System (although it is frequently also called Automatic Position Reporting System.)
APRS was developed in the early 1990's by Bob Bruninga, WB4APR, for digital communications and tracking mobile GPS equipped stations utilizing Amateur two-way radio.

4. Bob Bruninga – “Father of APRS”
His first connectionless protocol was run on a VIC-20 program in 1984 to report the position and status of horses in a cross country endurance run for AMRAD
One of his first applications for APRS while an Instructor at the Naval Academy in Annapolis, MD. was to assist in tracking Academy boats on summer cruises up and down the Atlantic coast.

5. Bob Bruninga – “Father of APRS”
The predecessor to the current “APRS” protocol was named APLS and released in 1991.
He is still very active today, and continues to provide support and set standards.
In the 13 years since its introduction, he has helped APRS to grow to the extent that it now encompasses just about every aspect of Amateur Radio.

6. What is APRS all about?
The APRS System was developed to provide immediate local digital and graphical information exchange between all participants in an event. This includes not only tracking and monitoring position data, but also status, messaging, bulletins all without having to maintain packet connections. Typical data:
Positions of all stations and objects
Status of all stations
Messages, Bulletins and Announcements
Weather data and telemetry
DF bearings and signal strengths for quick transmitter hunting
Typical applications are:
Marathons, races, events and public service
Search and rescue
Family communications and tracking and one-line s
Mobile-to-mobile global messaging
Weather data exchange and display

7. More “About APRS”….
APRS consists of a very large land based wireless network. Almost 30,000 users around the world.
This network works via RELAYS every miles called “digipeaters.” And Globally via IGates to the internet.
APRS is also used via some of the Amateur Satellites.
It is also used to monitor telemetry values of weather stations for the National Weather Service (NWS)
APRS has the capability to quickly relay telemetry values to research centers without the Internet.

8. Different than Regular Packet
It uses graphical maps and other data displays.
All communications use a “one-to-many protocol” so everyone is updated in real time.
Uses Generic digipeating so knowledge of the network isn’t required.
APRS turns packet radio into a real-time tactical communications and display system for emergencies and public service applications.

9. What Equipment is required?
APRS was developed to use exsting packet radio hardware, so it only needs three pieces of hardware.
a transmitter/receiver (Transceiver),
a packet terminal node controller (TNC).
An optional Global Positioning System (GPS),

10. Basic Equipment - Radio
A VHF Amateur Radio Transceiver operating on Mhz. (USA).
Should be a “transceiver” as APRS uses a collision detection system to know when to send data.
Range of coverage depends on the power of the transmitter and terrain.

11. Basic Equipment - GPS A standard GPS (Global Positioning System) unit.
Uses 24 orbiting satellites to pinpoint anyone's specific geographic location.
GPS also provides ground speed and altitude measurements.
Current accuracy ranges from feet.

12. Basic Equipment - TNC
A TNC which is basically a radio (or “RF”) modem.
The TNC connects the transceiver to a GPS converting it’s data into AX.25 Packet protocol.
“TinyTracs” are simple “Transmit Only” stand alone APRS TNCs

13. Various Mobile Setups
Mobile Tracking Installations utilize a GPS connected to the radio through the TNC interface,
The new “APRS Ready” transceivers like Kenwood’s TM- D700 have their own built in TNC.

14. Various Portable Setups
A Portable Tracker is usually low powered and may need a nearby digipeater.
These units work well with bike-a-thons, parades and other community events, along with search & rescue operations and weather nets.

15. Weather Station Setups
Weather station setups with APRS are similar to the normal setups,
However, the GPS unit is usually replaced by outside Weather Monitoring Equipment.

16. Built-in TNC Function Radios
These radios are specifically designed to support APRS functions in a single package. Just add a basic GPS unit and it is ready!
Kenwood TM-D700A (includes front panel display)
Kenwood TH-D7A (includes front panel display)
Alinco DR-135T MKII with EJ-41U TNC

17. Kenwood TM-D700A A Dual band 144/440 MHz 50/35 Watts
Built-in 1200/9600 bps TNC including a “digipeater”.
Built-in screen display of other APRS stations and front-panel send/receive messaging.
Add a GPS, and the proper cable, or simply key in your position coordinates.
Other APRS station locations are sent to the attached GPS map for display.

18. Kenwood TH-D7A(G) Built-in APRS functions and displays.
Dual band 144/440 MHz.
Built-in TNC at 1200/9600 bps.
On screen text monitoring & messaging
Plug in a GPS or key in coordinates
Attached GPS map displays all other
APRS station locations

19. Alinco DR-135T/EJ-41U Basic 2 M Radio with optional TNC.
Allows direct input from any standard GPS.
Basic 1200/9600 bps TNC
Unlike the Kenwood radios, it requires a PC to set it up, and there is no APRS display directly on the radio.

20. PC Soundcard Method…
Use a PC sound card to transmit and receive signals from radio – No TNC required
AGWPE is an excellent Sound card interface for Packet Radio available free on the Internet.
Simple interface circuitry (The same as PSK31).
Requires a modest computer to operate

21. APRS Voice Alert
Voice Alert is effectively 3rd Radio channel for the D7 and D700 APRS radios
By setting the Band A for APRS to PL-100, but keeping the volume turned up:
You wont hear any packets on *
But you will hear a voice call using PL-100 on
And you will hear* an occasional Ping packet if another D700 comes in line-of-site to you, like a proximity radar alerting you to local presence.
Great for long haul traveling and meeting other APRS users.

22. How does the Signal Travel?Aa
Direct Relays

23. How does the Signal Travel?Aa
Relays and DigiPeaters

24. How does the Signal Travel?Aa
Straight through the DigiPeater

25. How does the Signal Travel?Aa
Multiple Hops

26. How does the Signal Travel?Aa
And to the Internet Gateway

27. The New-N Paradigm 2005
APRS Generic Paths evolved over 13 years and the presence of many old legacy formats and procedures were really bogging down the network making it saturated and unreliable in busy areas.
In 2005 all old paths were declared obsolete (RELAY & WIDE) and the entire APRS system in the US was then focused only on the WIDEn-N type of generic paths with small values of N.
A WIDEn-N path goes N hops outward in all directions.
N=2 in most areas colored on next slide

29. Mapping/Tracking Programs
APRSdos Bob Bruninga
WinAPRS Mark Sproul
MacAprs Keith Sproul
APRS+SA Brent Hildebrand
UI-View Roger Barker
Xastir Open Source
XAPRS Sproul Brothers
PocketAPRS Mike Musick

30. APRSdos The original, runs on any PC. Even a 386 or 486 & 1 floppy.
Its focus is on the network, the RF channel, and local communications and display. Has crude maps.
Only program with all APRS features built in
Only APRS that fully supports all DFing modes
Has lots of tools for assessing and displaying the local network, station ranges and RF connectivity.

31. APRSdos (Range Circles)

32. APRSdos (ALOHA circle and digipeater hops) [Your ALOHA circle is your 100% saturated channel range]

33. APRSdos Range circles and Path tracing

34. APRSdos ( DFing by signal strength )

35. APRSdos 3D views for Balloon tracking

36. APRSdos Tracking with Milemarks

37. APRSdos ( Solo DF Fade Circle Technique )

38. WinAPRS and MacAPRS Separate Windows and Mac programs
Precision Mapping and Tiger Maps
Supports GPS and weather station input
Supports all standard Packet Radio TNCs
Supports all standard callbook CD-ROMs for lookup of call signs

39. WinAPRS (TigerMaps)

40. WinAPRS

41. WinAPRS

42. APRS + SA 32-bit Windows-based Delorme Street Atlas 4.0 through 9.0
TNC-2 or AGWPE for RF operation
Standard NEMA GPS and Weather station support
IGate to Internet
send and receive
Web Server

43. APRS + SA

44. APRS + SA

45. APRS + SA

46. APRS + SA

47. UI-View
UI-View uses bitmap images for its maps. Also, the 32 bit version supports Precision Mapping.
It supports TNCs in KISS mode and AGWPE host mode in addition to terminal mode - and host mode allows up to 16 RF ports.
UI-View has a full-featured intelligent digipeater.
UI-View has full support for connecting to APRS servers on the internet.
UI-View is open architecture. A number of other software developers have written add-on applications providing additional functionality.

48. UI-view
Whether it is used just for WX, or display only, or full TX /RX/internet. UI-View is more than capable.
It can be configured as a digipeater to relay packets.
With plug-ins, UI-View can receive NWS warnings and plot them on the map.
UI-View can really shine in the emergency or event communications role.

49. UI-view Maps
Full support for Precision mapping, plus you can “capture” many other mapping programs.
SA virtual map. It makes it very easy to grab maps from Street Atlas V4, V5, V6, V7, V8 and V9
UI-Terra add-on allows you to make maps from Terraserver.

50. UI-View Events Operation
Exclude/include lists. Here you can choose to exclude everything except mobile stations.
Tactical calls -- you can assign labels to call signs.
With a plug-in, you can draw an object on the map and transmit it over APRS. This is great for a race route.

51. Xastir
Development is a collaborative effort of programmers from around the world.
Xastir supports many map formats and is highly customizable.
Xastir runs on Windows, MacOSX, Linux, FreeBSD, Solaris, and Lindows, with many more possible .
On Unix-like operating systems, you can run your weather station or GPS on a separate computer as well, which is good for those hams who are already short on serial ports.
Xastir is FREE! under the GPL license and comes with all source code.

52. The APRS Internet Interface
Allows you to see more than just local RF.
Utilize facilities available only on the Internet.
Low cost backbone between RF networks.
World-wide availability.
Can run stand-alone without a Radio Interface.

53. APRS IGates
An IGATE is a local APRS station that utilizes the APRS-Internet network to pass all packets heard on their local RF back to the Internet.
It can also act as a gateway to pass messages addressed to local RF stations from Internet only stations.

54. Findu.com mapping
Internet tracking developed by Steve Demise – K4HG

55. Findu.com Weather Tables
Temperature & Dew Point
Rainfall Rates

56. Field Day 2004 at Beltsville
Aprsworld.com
Developed by James Jarvis – KB0THN
Field Day 2004 at Beltsville
Home Weather Station
On my way to Work
Allows simultaneous tracking mapping of the various SSID’s used by a station

57. Citizens Weather Corps
The Citizens Weather Observer Program (CWOP) has become an interesting adjunct to the APRS Internet reporting system.

58. WXNET and CWOP Purpose
Allows non-Amateurs to utilize the APRS network to collect and report on local weather conditions.
Does not require any kind of Radio Interface
This data is available as a public service for any non-commercial use.
Provides feedback and guidance to weather
station operators to help them improve.

59. APRS for Special Uses Bicycle rallies, races Walk-a-thons, Parades
Skywarn
Weather Nets
Crime prevention patrols
Damage assessment
Direction Finding – Foxhunts
Voice for communications, APRS for visual mapping
Now integrating into APRN (Automatic Picture Relay Network)

60. Into Space..PCSAT APRS space frequency is published as 145.825
The Prototype Communications Satellite, is a US Naval Academy Aerospace student project.
It was designed to give students real hands on experience in satellite design and operations
APRS space frequency is published as

61. APRS via Space
APRS space frequency is published as

62. PCSAT, Launched in September 2001 from Kodiak Alaska Launch Complex.
The first APRS satellite, and has since been joined by 3 other such satellites
It still works during mid-day sunny passes.
PCSAT Satellite
See live downlink on

63. PCSAT Enhancements
PCsat includes a special store-and-forward Priority Communications feature.
This can capture Emergency and Priority messages from the Kenwood THD7 and D700 radios anywhere on the globe and retransmit these signals on the USA VHF APRS frequency.

64. International Space Station
International Space Station (ISS) also supports APRS on its / packet system.
Use digipeater path VIA ARISS.
Also has been used by the crew to send messages to friends, family, and amateur radio operators
See live downlink on

65. PCSAT2 PCSAT2, is the second APRS digipeater satellite.
Use digipeater path VIA ARISS.
It was attached to the outside of the ISS in July 2005
Uplink is downlink is
See

66. Credits
Thanks to the following for earlier research and presentations on APRS…….
John Beadles N5OOM
Tony Campbell W5ADC
Pete Loveall AE5PL
Bob Bruninga WB4APR (updated Jan 2006)